It is well known that polyesters, such as polyalkylene terephthalates, for example, polyethylene terephthalate and polybutylene terephthalate, and alkylene terephthalate copolymers, exhibit excellent physical and chemical properties, and, therefore, are useful as various textile materials. That is, the polyester filament yarns are widely used for producing various woven or knitted fabrics.
However, it is also known that conventional polyester filament fabrics exhibit poor dry touch and opaqueness. This nature of the polyester filament fabrics are quite different from that of natural silk fabrics.
In recent years, bulkiness, draping property and resilience of the polyester filament fabrics were significantly enhanced by improvements in the technology for the production and processing of the polyester filament fabrics. These enhanced properties are very close to those of the natural silk fabric. However, the disadvantages in the dry touch and opaqueness of the conventional polyester filament fabric has not yet satisfactorily been removed. Therefore, it is strongly desired to modify the polyester filament fabric so as to cause the modified product to exhibit a silk-like configuration (appearance) and dry touch.
For this purpose, various types of polyester filaments having an irregular cross-sectional profile, especially, trilobate or star-shaped cross-sectional profile, were prepared. Those types of the polyester irregular filaments caused the resultant fabrics to exhibit a different luster and touch than those of the conventional polyester filament fabrics in which individual filaments had a circular cross-sectional profile. However, the polyester irregular filaments having the tribolate cross-sectional profile also exhibited a different luster and touch than those of the silk fabrics. That is, the luster of the polyester irregular filaments was undesirably metallic and the opaqueness, bulkiness and softness of the polyester irregular filament fabric were unsatisfactory.
Also, in the case of the polyester irregular filaments having the star-shaped cross-sectional profile, the luster was closer to that of the silk fabric than that of the polyester filaments having the trilobate cross-sectional profile. However, this type of filaments failed to exhibit a satisfactory opaqueness and touch. Also, the filaments exhibited an unsatisfactory bulkiness because a plurality of the lobes in the star-shaped cross-sectional profiles of the individual filaments cause the movement of the filaments from each other to be restricted.
In order to eliminate the above-mentioned disadvantages of the polyester filaments having the trilobate or star-shaped cross-sectional profile, another type of polyester filaments having a C-shaped, L-shaped or V-shaped cross-sectional profile were provided. This type of the polyester filaments could cause the resultant fabric to exhibit significantly reduced metallic luster. However, the opaqueness and touch of this type of the polyester filaments were unsatisfactory. Also, its bulkiness was unsatisfactory because the leg portions of the C-, L- or V-shaped cross-sectional profiles in the filaments were linked with each other.